Radial tire with bias cut woven nylon chafer fabric

ABSTRACT

A wick proof woven chafer fabric for automotive radial tires has a monofilament fill yarn and a textured multifilament warp yarn. The chafer fabric comprises nylon yarns and is bias cut so that the warp and fill yarns extend at an angle to the bead of the radial tire.

BACKGROUND AND SUMMARY OF THE INVENTION

This invention relates general to pneumatic radial tires and morespecifically to chafer fabric for such tires to prevent abrasion of thetire with the wheel rim flanges when mounting and dismounting suchtires.

Automotive tires as traditionally constructed employ as a carcass apolymeric material, such as robber, reinforced with textile cords andsteel belts. The wheel engaging portion of the tire is furtherreinforced by circumferentially extending cores of wire or otherrelatively rigid material known as "beads". Extending at least partiallyabout these beads and on their surface are "chafer strips" which areintended to resist abrasion of the tire by the rim flanges when the tireis mounted and dismounted.

Chafer fabric is conventionally prepared by flat weaving a fabric,wick-proofing and then friction calendering green robber to both facesof the flat woven fabric and then bias cutting and slitting thecalendered fabric into strips of from 1 to 5 inches in width. The stepof friction calendering green rubber to the woven fabric and/or skimcalendering is carried out to facilitate the ease of bias cutting andpiece lay up in green tire building, as well as promoting thevulcanization of the components making up the tire body in the finalproduct.

It should be understood that the chafer fabric of this invention is awoven chafer fabric, that is to say a fabric having substantiallystraight warp and filling threads interlaced at substantially rightangles. A woven fabric should not be confused with a braided or plaitedfabric wherein individual threads are skewed and are intertwined atacute angles with each other. Plaited fabrics are not useful as chaferfabrics due to a lack of dimensional stability of the fabric structure.

It is therefore an object of the invention to provide a chafer fabricfor tires which can be readily wick-proofed, calendered and molded.

Historically chafer fabrics have been produced out of cotton, but withthe advent of the tubeless tire, the yarns in the chafer fabric had toprevent the high pressure air inside the tire from wicking (bleeding)along inside the yarn bundles and reaching outside the rim. If the aircan reach the outside tire surface, the tire will slowly lose pressureand gradually go flat. Therefore a wick-proof fabric is essential in thepreparation of tires of the tubeless type, and especially high pressuretubeless tires.

For purposes of this invention, the term "wick-proofing" may be definedas a process wherein each cord of a fabric sheet is made impervious tothe passage of air. In tubeless tires, high air pressure in the aircavity pushes against the inner surface, and significantly at the beadarea, and if the fabric in the chafer is not impervious to the passageof air, air will penetrate the individual cords which then serve asconduits to wick air into the tire body causing blistering anddelamination of rubber or leading to the outside atmosphere therebyreducing the internal load supporting air pressure of the tire withundesirable results. Any of a wide variety of wick-proofing processesare satisfactory for use in conjunction with this invention, such as,for instance, wick-proofing processes of the type set forth in U.S. Pat.No. 2,978,784.

In conjunction with tubeless tires, rayon, nylon, and polyestercontinuous filament yarns became available, and these fibers required anadhesive finish which would adhere to the rubber of the tire. Withmultifilament yarns bundles this finish (generally referred to as RFL)can penetrate to the core of the yarn bundles (if proper procedures arefollowed) and block the passage of air. Monofilament yarns, typicallynylon, are wick-proof by their nature, and only a small amount of RFLadhesive is needed for adhesion to the rubber.

Monofilament yarns (typically T-6 or T-66 nylon) are widely used aroundthe world because of the guaranteed wick-proof characteristic. However,the monofilament yarn size must be kept small (380-440 denier) to keepit flexible, and therefore it is weak in tensile strength. For the wovenfabric to be strong enough to withstand the tension applied during thetire industry's rubber calendering process, the warp construction mustbe kept relatively high, typically 22-25 ends/inch. Since chafer fabricsare generally used after being cut on the bias, the pick count istypically the same as the warp end count, 22-25.

The use of higher tensile, larger denier multifilament yarns ranging insize from 840-1260 denier, with the most common sizes being 840 and 1000denier, is possible due to the flexibility provided by the many finerfilaments these larger yarn bundles are comprised of. These yarns areeither twisted or textured for processability through the textilemanufacturing processes. Due to the higher strength, constructions inthe range of 12 ends and picks to as high as 18 ends and picks are used.An inherent need of these multifilament yarns is to be impregnated tothe core of the yarn bundle with RFL to make them wick-proof. Toreliably accomplish this, dip pick-up levels range from 14% to as highas 35%. Monofilament yarn dip pickup, on the other hand, ranges from 3%to 9% which only has to impart satisfactory adhesion--notwick-proofness.

It is another objective of this invention to combine multifilament andmonofilament yarns in one chafer fabric to optimize utilization of theirphysical properties while incurring minimum cost in the fabric. By usingmultifilament yarn in the warp, either twisted or textured, andmonofilament in the filling, warp tensile strength can be maintained atan adequate minimum level, 160 lb.fin. (grab method) while using a lowend count (12-18 ends/in.). Since filling direction tensile is notcritical to processing or performance in the tire, the monofilament yarncan be used in this direction at a possible range of 12-18 picks/in. Thedip pick-up in the warp will provide the wick-proof property while stillallowing the multifilament yarns remain flexible. The monofilamentfilling will only pick up enough RFL to provide adhesion, and the lowerdenier and low pick count will maintain filling direction flexibility.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and advantages of the invention will become clearlyapparent as the specification proceeds to describe the invention withreference to the accompanying drawnings, in which:

FIG. 1 is a schematic of a conventional automotive tire showing therelationship of the various components of the tire; and

FIG. 2 is a plan view of the new and improved chafer fabric used in thetire shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Looking now to FIG. 1 a typical tire construction is shown in schematicfashion.

Basically the tire 10 consists of three sections, the tread area 12, thesidewall/shoulder area 14, and the bead area 16. The tread area 12 iscomposed of primarily of the tread cap 18, which is directly over thesteel belts 20, which are centered on the upper surface of the tire cordfabric ply 22. The sidewall/shoulder area consists primarily of the tirecord fabric 22, additional rubber strips and the upper portions of theturned up flipper 24 and chafer strips 28. The bead area consistsprimarily of the bead wire 26, the flipper 24, the chafer 28, and thetire cord fabric turn up 30.

As briefly discussed before, the chafer fabric 28 is a rubberimpregnated fabric, in the form of bias cut strips, which is applied tothe bead area 16 of the tire in green tire construction. Originally thechafer strip was employed to reduce the chafing effect between the tireand the tire rim and to protect the plies underneath as well as aidingin producing bead shape and firmness in the bead area. In tubeless tiresit provides the further function of preventing pressurized air fromdiffusing through the chafer yarns into the side wall or to theatmosphere causing sidewall blisters and the tire failure, or a flattire. Therefore, these chafer yarns must be wickproof.

For use as chafer fabric, it is desired to employ a woven fabric whichhas a low end count. To this end, the chafer fabric 28, as representedin FIG. 2, is a standard woven fabric having a monofilament syntheticnylon fill yarn 32 and a multifilament synthetic nylon warp yarn 34. Inthe preferred form of the invention the fill yarn is about 420 deniermonofilament nylon 6,6 yarn and the warp yarn is about 900 deniertextured nylon 6, 6 multifilament yarn.

The above described chafer fabric 28 is a 14×14 plain weave but ifdesired, can be a balanced or unbalanced weave having 10-25 end per inchand 10-25 pick per inch with an RFL finish. The preferred multifil warpyarns are nylon 6, 6 but other yarns such as nylon 6, polyester, rayon,etc can be employed. Nylon 6, 6, nylon 6 or polyester can be used as themonofilament fill yarn. The warp yarn can be twisted or textured. Thedenier of the warp yarn can be in the range of 400-1400 denier and thefill yarn can be in the range of 200-720 denier. The weight of thechafer fabric can vary from 2.0-5.4 oz/yd² and of any weave type such asplain, twill, basket, oxford, or satin weave.

While the above yarn selections and construction will optimize classicproperties at lowest practical cost, there is another property that willbe optimized. Chafer fabrics are typically open plain weaveconstructions so that rubber will flow through the interstices and imbedthe fabric in the rubber at the surface of the bead area. Warp yarngenerally stays straight and round in shape due to the warp directiontension constantly applied during weaving and RFL finishing. The fillingyarns if multifilament (and particularly texturized) tend to flattenout, as there is little or no tension kept on them once the fabric iswoven and during RFL application. As they flatten, they close up theinterstices making them smaller and may even be plugged. Thesemultifilament filling yarns, being soft and supple, also tend to shiftcausing a distorted and non-uniform weave. Monofilament yarns on theother hand maintain their cross-sectional shape and do not flatten outby their nature, and because of their inherent stiffness they staystraight and uniformly spaced across the fabric. The result of the aboveis larger and more uniform interstices than found in a standard 100%multifilament chafer.

Another potential benefit of this fabric design is the ability toproduce a tucked filling selvage that is acceptable to the rubberindustry. Currently the tucked selvage created by many modern weavingmachines is too dense a construction for chafer if multifilament yarnsare used. Current practice is to slit the selvage off after finishing.This is costly, creates a land fill problem, and reduces the selvagestear resistance. 100% Monofilament chafers with tucked selvages arebecoming accepted, even at their higher pick count, because thesesmaller diameter yarns still allow rubber strike-through. By tuckingmonofilament filling at low pick count, the rubber strike-through issatisfactory even with the multifilament warp yarns. The resultingselvage is strong and processes well at the calender in the tire plant.

In summary, this invention combines the use of two forms of syntheticyarns in one chafer fabric to achieve the following:

1.) Optimum performance and processability of the chafer from the uniqueproperties of each yarn.

2.) Optimum low cost due to utilization of yarn sizes to meet tensilerequirements.

3.) Optimum low cost due to low RFL consumption by the monofilamentyarn.

4.) Excellent weave quality due to the stiffer monofilament fillingyarn.

5.) Superior strike-through due to the non-flattening monofilamentfilling and the tension rounded multifil warp.

6.) Superior selvage due to the tucked monofilament filling that stillallows satisfactory rubber strike-through.

7.) Further cost reduction due to elimination of the selvage cuttingprocess plus the retention of the selvage yarns in the usable body ofthe fabric.

8.) An environmental benefit in that the trimmed selvage material nolonger is baled and hauled to the land fill.

Although I have described the preferred embodiment of my invention, Icontemplate that many changes may be made without departing from thescope or spirit of my invention and I desire to be limited only by theclaims.

What is claimed is:
 1. In a tubeless tire having a bead area, asidewall/shoulder area and a tread area, the improvement comprising awickproof bias cut chafer fabric in the bead area for abrasionresistance during the mounting/dismounting of the tire to a rim, saidchafer fabric being a woven fabric constructed of a nylon monofilamentfill yam and a textured nylon multifilament warp yam having a denier inthe range of 400-1400, said warp and fill yams both extending at anangle to the bead area of the tire.
 2. The tire of claim 1 wherein thefill yarn has a denier in the range of 200-720.
 3. The tire of claim 2wherein the warp yarn is about 900 denier.
 4. The tire of claim 3wherein the fill yam is about 420 denier.